To provide an inclination monitor device which can easily monitor the inclination of an object without contact.

A light source 3 and a light reflector 4 are placed at a subject 1 and a photocell 5 is placed on a fixed part 2 facing the subject 1. The light reflector 4 is driven vertically and horizontally by a control circuit 6 and a drive circuit 7 so that light reflected from the light reflector 4 is scanned over the photocell mounting surface of the fixed part 2. The time from the start of the scan to the reception of the reflected light by the photocell 5 is measured by a time measuring circuit 8, and a determining circuit 9 determines whether or not the attitude of the subject 1 has changed according to the result of the measurement.